Foster Company is considering whether to sell Retox at the split-off point or subject it to further processing and produce a more refined product nown as Retox-F. Consider the following items 1. The selling price of Retox-F. II. The joint processing cost of Retox. III. The separable cost of producing Retox-F. Which of the above items is (are) relevant to Foster's decision to process Retox into Retox-F? I only. I and III. II only. I and II. Ill only.